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Overclocking my Sapphire 7950 Vapor-X

Discussion in 'Overclocking & Cooling' started by hawk767, Jun 21, 2013.

  1. hawk767

    hawk767

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    I've had the card a couple months and am just started playing with overclocking it.

    Right now I have it at 1150/1450 stable but each time I bump it to 1500 memory clock it crashes. So from here do I need to increase my voltage, the VDDC option in Trixx?

    So far I've been running tests with the Heaven Benchmark on custom settings,

    Quality: High
    Tessellation: Normal
    AA: x4
    1920 x 1080
    DX11

    This is my first time toying with a gpu so I just want to be sure I don't fry something haha.

    Temps have sat around mid 60's only jumping up to 66+ now that I've bumped by memory up to 1450. I'm curious as to what would be better to have raise higher now, the memory to that 1500 that I read of many people reaching or the core clock to 1200+.
     
  2. buildzoid

    buildzoid

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    The HD7950 has a 384 bit bus the memory is less important than core speed. Though if you want you could get after burner and use the VRAM voltage increase option to get a little more VRAM speed using 1.6-1.65v but it's riskier than pushing 1200mhz on the core using 1.2-1.3v because you can inflict permanent damage on the VRAM.
     
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  3. hawk767

    hawk767

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    As far as I've read 1500 memory clock seems to be the max you can get on air so is the memory clock what is requiring a voltage jump or the core clock.

    I used CCC's overdrive to set my power at +20% and the max volts I've seen is only 1.28 - 1.29 on GPU-Z and that's at 1400 memory clock. Will another bump of 50 really require that big of a voltage increase?
     
  4. buildzoid

    buildzoid

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    Send me a screenshot of GPU-z voltage readings. Because if that's voltage on the memory that it's reading then you have some really low power GDDR5 or GPU-z is reading it wrong as most cards have voltage between 1.5-1.6v on the VRAM at stock
     
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  5. hawk767

    hawk767

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    Ok then I assume that the voltage is the MVDDC which reads a steady 1.602 V both idle and under load. I was thinking that the voltage was just the VDDC which under load is reading 1.238 as the max reading at 1150/1450. The only option available to change in trixx is the VDDC so I'll check out afterburner and see if that gives me anything.
     
  6. buildzoid

    buildzoid

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    Ok good. Set the MVDDC to 1.65v and no more. If it doesn't help put it back down to 1.6. So I if read right you're already pushing 1.3v on the core because that is about as far as I would push it. So if the MVDDC increase does nothing for mem clocks give up as 1200/1500mhz isn't much faster than 1150/1450.
     
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  7. hawk767

    hawk767

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    Now when I'm toying with Afterburner I'm able to change the voltage settings both core and memory.

    Core Voltage: 1125
    Memory Voltage: 1600

    Now when I change the mV there is no voltage change on gpu-z it remains to show 1.602 instead of 1.625 which is what I try setting it to. I've read about this card being possibly volt locked or is it just the BIOs.

    Edit: After a bit more toying with it all I think 1200/1400 is my max. I have my VDDC set to 1275 rather than 1300 and it ran fine on the tests I ran. I was able to bump my VDDC to 1300 and run my core up from 1210 - 1250 but the higher it got the more artifacts were showing up in Heaven Bench so I just dropped it back down.

    These Heaven scores were all run with the same settings I showed in the beginning of the thread.

    Windowed 1200/1400: 1402
    Fullscreen 1200/1400: 1344
    Fullscreen 1225/1400: 1354


    The performance increase from the core after 1200 just isn't much unfortunately. My temps sat fine in the high 60's as well once I bumped the VDDC. 71 being max card temp and 73 being the VRM 1 and 2 temps.

    The 1250/1400 test I stopped early because the artifacts were very noticeable.

    I guess I can just overclock my cpu now at some point and to get further performance.

    Edit 2: Running the Heaven Benchmark on Extreme,

    Ultra Quality
    Extreme Tessellation
    8x AA

    I managed a score of 887, max fps 77, min 14. So not bad I suppose. No crashes or problems so far but I'll see how long that holds while gaming.

    I assume its just fine to keep it at normal boost settings, 950/1200 and bump it to my OC whenever I'm going to play a graphically intensive game?
     
    Last edited: Jun 21, 2013

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